1. Technical Field
A present invention relates to a droplet-discharging device and an electro optic device.
2. Related Art
A liquid crystal display generally comprises oriented liquid crystal molecules and an orientational film made of orientational polymer such as orientational polyimide, which arranges orientation of liquid crystal molecules. An ink jet method using a droplet-discharging head is applied to a process for manufacturing the oriented film in order to improve productivity and reduce a manufacturing cost. (see JP-A-2004-347694.)
The droplet-discharging head comprises a plurality of cavities storing liquid, a plurality of nozzles arranged in a row and connected to cavities, and a plurality of actuators such as piezoelectric elements and resistive heating elements. The droplet-discharging head receives input signals that commonly drive an actuator selected among a plurality of actuators based on drawing data and discharges liquid droplets from a nozzle corresponding to each actuator. An inkjet method forms the oriented film by applying a material for the oriented film to a droplet-discharging head, discharging liquid droplets including orientational polymer molecules to a substrate and drying liquid droplets landed on a substrate.
In an inkjet method, a droplet-discharging head relatively moves toward a predetermined scanning direction against a substrate to which droplets are discharged and each of actuators receives above driving signals with a predetermined discharging frequency. Such method draws a pattern of a liquid body in order along a scanning direction on a substrate where a pattern is drawn by discharging liquid droplets of which amount corresponds to numbers of arranged nozzles with a predetermined discharging frequency in order.
A droplet-discharging head provides a liquid body to all nozzles from a common single tank. Such providing, however, causes a following problem. Namely, when a droplet-discharging head discharges many liquid droplets from nozzles at a same time, different flow channel resistances among nozzles cause different supplying pressures of liquid droplets, yielding a crosstalk among adjacent nozzles, and largely fluctuating discharging amounts of liquid droplets among nozzles. As a result, relatively large sized droplets or relatively small sized droplets are continuously discharged along a scanning line, forming thickness steps along a scanning line of a droplet-discharging head and remarkably deteriorating display quality of an liquid crystal display.